Windshield wiper and similar mechanism



June 17, 1941. 'F. E. Twiss 2,245,626

WINDSHIELD WIPER AND SIMILAR MECHANISM Filed Sept. 28, 193'? 4 Sheets-Sheet l 1230622 tar; jravzki, jazlss, I (4093 JJ/MW A tis.

June 17, 1941. F,'g,Tw.|$s 2245 326.

WINDSHIELD WIPER AND SIMILAR MECHANISM Filed Sept. 28, 1937 4 Sheets-Sheet 2 1220622 tar; frank 11 T uss; by WI I A it June 17, 1941. F. E. TWISS 2,245,626

WINDSHIELD WIPER AND SIMILAR MECHANISM Filed Sept. 28, 193 7 4 Sheets-Sheet 4 i 27 M4 405 I a Ina en Z07; Frarzitfl Jwss,

y MM W Atts:

Patented, June 17, 194

' 2,245,626 wmnsnmw wrrag lg n snmhn MECHA- Frank E. Twiss, 'launton, Mass, assignor to F. E.

Twiss Co Inc., Boston,

usetts Mass, a corporation of Application September 28, 1937, Serial No. 166,066

Claims.

sive to the variable vacuum in the inlet manifoldof the motor, or of the electrically driven type wherein an electric motor, including a continuously revolving armature, was effective through suitable gearing in imparting an oscillating movement' to the wiper blade support. The vacuum operated mechanisms have had the commonly recognized disadvantage of being subject to wide variations in speed of operation dependent upon the changes in the vacuum in the inlet manifold. Thus under certain driving conditions the rate of wiper movement became undesirably slow, resulting in serious obstruction to vision by droplets on the portion of the windshield which should be kept clean by the wiper blade. On the other hand, while electrically operated wiper mechanisms of the type referred to had a certain vogue, such mechanisms were found unsatisfactory due to the wear imposedby the reciprocating mechanical parts, the looseness developing in the gearing, and the need for lubrication which often was not attended to, with consequent wear and increase in noise of the operating mechanism, and particularly of the gearing. Furthermore, such motors were commonly supplied with commutators and brushes which were subject to wear and were not dependable over long periods of time.

The present invention affords a windshield wiper mechanism which avoids these deficiencies in the prior art, being operable at a desired optimum speed irrespective of the conditions under which the motor of the vehicle is operating and entirely independently of the vacuum in the inlet manifold, while this invention also avoids the gearing, the numerous bearings, and the commutator and brush assembly which characterized previous electrically operated windshield wipers.

To permit these desirable results, the present invention affords a simple compact wiper assembly which may include an electrical power unit which is free from parts requiring lubrica-v tion or attention. The device also includes hydraulic power transmitting" means of a simple type which is effective in causing the movement of the windshield wiper support back and forth without necessity of employing gearing, oscillatory'racks or the like.

In accordance with; this invention, the electrical power unit may comprise electromagnetic means, preferably of the solenoid type. and may conveniently include a plunger movable within the coil and secured to a vibratory diaphragm, the diaphragm carrying one contact of a makeand-break mechanism. Such an electrical power unit is arranged so that the vibratory movement of the diaphragm and armature assembly including the plunger, results from energization of the solenoid coil, the action being similar to that provided in many electrically actuated warning signals of thevibratory diaphragm type.

Associated with the diaphragm assembly are suitable chambers and passages forming parts of the hydraulic power transmitting system, and a check valve is carried by the assembly so that, when the plunger moves in one direction, small bodies of hydraulic fluid pass through the valve, which is thereupon closed and moves in the other direction with the rest of the assembly that is thus efl'ective in giving a slight power impulse tending to cause the circulation of the hydraulic fluid through the passages and chambers provided therefor. Since the diaphragm assembly is vibrated at a rapid rate, a substantial current of hydraulic fluid or oil is thus circulated through the various es and chambers. One of these chambers contains an oscillating vane, one face of which receives the pressure of the current of oil so that the vane is moved in the-chamber.

A suitable windshield. wiper support is connected to the oscillating vane so that, as the vane is oscillated, the wiper blade itself may have a corresponding movement. In order to permit the vane and wiper support to move back and forth, suitable valve means controls the flow of the hydraulic fluid into the vane chamber so that hydraulic pressure is imposed upon one face of the vane to move it in one direction until it approachesthe end of its path in that direction, whereupon the valve is actuated so that hydraulic pressure is then imposed upon theopposite face of the vane to move it in the other direction. Suitable means is associated with the vane shaft to actuate the valve at each end of the vane stroke or path so. that this action automatically takes place during operation of the device.

A further advantageous feature of the invention relates to the provision of electrical control means adapted to permit the operation of the wiper or the interruption of such operation as is desired, but arranged so that the wiper support.

is closed, whereupon the blade may automatically return to one end of its path due to momentary operation of the wiper mechanism, which occurs under such conditions even although the wiper control switch remains open. 1

In the accompanying drawings:

Fig. l is a sectional view of a portion of the windshield and front header of a motor vehicle. with my improved windshield wiper mechanism shown in elevation as mounted thereon;

Fig. 2 is an enlarged section through the wiper operating mechanism indicated by line 2-2 of Fig. 1;

Fig. 3 is a plan view of the control valve member of the hydraulic power transmitting mechanism;

Fig.4 is a section on line 4-4 of Fig. 8;

Fig. is a section indicated by line H of Fig. 4;

Fig.6isasectiononlinet-JofFig3;

Figs. '1, 8, 9 and 10 are sections indicated respectively by lines 'I -'I, H, H, and Il-Il oi Fig. 2; I

Fig. 11 is an elevational detail of a portion of the valve controlling and electrical control mechanism with a part broken away and shown in section;

Fig. 1215 a section on line I2I2 of Fig. 11;

Fig. 13 is an isometric view of a' contact arm employed in the apparatus and shown in Fig. 8;

Figs. 14 and 15 are sections indicated respectively by lines I4-I4 and Ii-Il of P18. 9;

Figs. 16, 17, 18, 19 and 20'are elevational details, somewhat diagrammatic in character, showing certain operating conditions of parts of the apparatus;

Figs. 21 and 22 are sectional details, somewhat diagrammatic in character, showing two settings of the control valve; and.

Figs. 23, 24 and 25 are broken elevational views of portions of the apparatus with wiring diagrams schematically associated therewith.

A windshield wiper mechanism constructed in accordance with this invention may comprise an operating unit included in a unitary casing I which preferably may be mounted, for example,

inside of the upper cross member I of a windshield 4. A wiper support 5 may be disposed outside of the windshield and may carry a conventional wiper or squeegee blade 6, the upper end of the support 5 being connected to a shaft 1 projecting from the casing I and extending through a. suitable opening in the windshield frame member 3.

The casing I preferably contains an electrically energizable power unit in the form of an electromagnetic element or solenoid III, and a suitable cooperating vibratory armature assembly. Thus the coil III of suitably insulated wire may be disposed near! one end of the casing I and within the same, and a diaphragm I2 of resilient metal is disposed adjoining one end of this coil. Thecoil may conveniently be mounted on a conventional spool of insulating material, the tubular inner portionof this spool, however, being extended to provide a collar lying within the opening in an annular metal plate I4, which fits within the wall oi the casing I, which preferably may be of cylindrical form. The member I4 preferably mayhave secures a washer 2| of insulating material against 7 the face of member II and secures a spacer II of such material and an overlying washer 22 of simiis: material in such a manner as to clamp an annulus 25 in spaced parallel relation to the member II. Secured to the diaphragm I2 is a metal contact disk 28 which is engageable with the contact plate 21 of the make-and-break mechanism. A flat spiral spring 20 is supported by the annulus 25 and is secured to a collar-like extension. 21' of the member 21 to support the latter. Thus in the normal inactive position of these parts shown in Fig. 2, the contact disk I. is engssins the contact plate 21, the spring 29 being slightly stressed under these conditions to constantly urge the contact plate to the right, as viewed in Fig. 2. Movement of the contact plate in such direction is limited by its engagement with the annulus 25; so that the circuit for the solenoid Il may be closed and the latter may then be energized. Thereupon, when the center of the diaphragm It moves towards the solenoid. the members 28 and The device is provided with a wall member 40 which is disposed at the inner end of the solenoid coil and supports an inner collar 48 in telescoping engagement with or juxtaposition to the end of the tube 38. The wall member 40 also provides a collar portion 40' which fits within the inner end of the tubular part oi the insulating spool of the solenoid II, it being noted that the end of the collar portion 40' and the edge of the annular wall of cup II are normally separated by a clear ance space, as shown, the width of this clearance space being reduced when the member II is magnetically pulled inwardly by the solenoid I0.

A relatively heavy coiled compression spring 4! is disposed between the wall 40 and a shoulder on the cup member 3|, thus tending to urge that member and the central portion of the diaphragm away from the solenoid coil. A very light coil spring 50 isdisposed between the end of the tube 43 and a flat annular washer 5|, which is normally held by the spring it over the inner ends of the openings 36 in the end wall of the cup member 3 I Thus the washer II forms a check valve which tends to be held in closed position by the light spring 50.

The wall member 40 is provided with a radial passage or duct 54 communicating at its inner end with the space surrounding the tubes 38 and 43 and in which the springs 49 and iii are located.

by one end of a tension spring 88. the opposite Y A sealing washer 88 of slightly compressible material, e. g., paper stocinis disposed between the face of the wall member 48 and an annular surface of a casting member 8|, there being an opening through this washer which communicates with the outer end of'the radial passage 54 in the wall 48, and with alongitudinal passage 82 in the casting 8! (see Fig.9). The casting 8| aflords a cup-like portion including a cylindrical wall section 85 which cooperates with the wall 48 in substantially enclosing an oil-containing chamber W. This chamber communicates, however, with the passages 88 by means of the openings provided in the telescoping tubes 88 and 48 previously described.

The passage 62 communicates with a duct 88 formed in the casting 8! (Figs. 2 and 14) while the other end of the duct 88 communicates with one or the other of two supply passages 88 and $8 in the slidable valve 10 (Fig. 4.) The valve 1! comprises a cylindrical member with the passages 88 and 69 drilled through the same and with right-angled outlet passages H and 18 at its outer ends. when the valve is in one position, shown in Figs. 9 and 21, the supply passage 88 registers with a duct 18 in the casting 8] which communicates with the vane chamber C and the outlet passage ll communicates with a e 14 in casting 6!, which in turn communicates with the opposite side of the vane chamber 0. When the valve 18* is moved to the opposite end of its path (Fig. 22), the supply passage 88 communicates with the passage '18 while the outlet passage I2 communicates with the passage 18. The outlet passages H and 12 are arranged to discharge oil from the vane chamber C therethrough to the chamber W (Fig. through passages H and 12', respectively, in the forward wall of the chamber W. The oil thus discharged into the chamber W is free to flow throughthe tube 88 to the inlet side of valve ii.

The end of the casting 8| is provided with a hollow portion defining the major part of the chamber C (Figs. 10 and 14), while a spacer plate 8i (Fig. 2) fits in registration with the end of the casting and is in turn engaged by the end wall 82 of the device. A portion or this wall member 82 provides one side wall of the chamber C. The shaft I extends through the vane chamber C and through wall member 82, and an oscillating vane 88 is secured to this shalt, having a substantially fluid-tight engagement with the walls of the chamber. Accordingly when oil is admitted to one side of the chamber C and passes out or, the other side of the chamber, the vane moves from the first side 01' the chamber toward the second side thereof. When this oscillatory movement in one direction has been completed, the position of the valve 18 is altered so that the direction of flow of oil into and out of the chamber 0 is reversed and the vane 80 moves in the opposite direction.

Suitable mechanism is provided to actuate the valve 18 at each end of the stroke of the vane. For this purpose the shaft 1 extends into the chamber W and carries a control plate 83 fixed thereto, while an, insulating disk 85 is loosely mounted'on the shaft 1 adjoining the plate 88, being spaced therefrom by a suitable spacing washer. The disk 85 is shown more particularly in Fig. 11 and is.provided with a rather short arcuate slot 86 which receives the end of a pin 81 (Figs. 2 and 8) projecting from the valve body 10, it being understood that the pin fits loosely within the slot. The insulating disk 85 is also provided with a pin 88 fixed thereto and engaged end of which is supported by a stud 88 projecting from the casting II.

The disk 88 is also provided with an arcuate contact strip 88 which extends about more than half of its periphery, as shown, ior example, in Fig. 11. The control plate 88 is provided .with arms or lugs 85 and 88 which engage thep'in 88 as the plate 88 moves toward one end or the other end of its oscillatory path corresponding to the oscillatory path of the vane 88. The lugs 88 and 88 engage the pin 88 to cause the disk 88 to move with the plate 88. This movement continues until the pin 88 is moved to the maximum distance from the pin 88, i. e'., to the uppermost point or its arcuate path as viewed in Fig. 8, whereupon the spring 88 is effective in snapping the disk 88 over center. so that the disk is moved to the position shown in Fig. 16 or that shown in Fig. 20. As such amovement occurs, relative movement takes place between the disk 85 and the pin 81, so that one or the other end 01 slot 88 engages pin 81 to cause the movement of the pin and valve Ill, thus reversing the position of the latter. Thereupon the vane 88, the shaft 1 and the control plate 88 move in the opposite direction, thisv movement continuing until a lug 88 or 98 on the plate 88 engages the pin 88, whereupon the insulating' disk 88 isagain' snapped over center by the. spring 88 and the position of the valve 18 is again changed.

when the device illustrated herein is in its normal operative condition, the spaces within the hydraulic power transmitting means aflord a closed system filled with oil. Thus these spaces include the chamber 0, the passages 18 and 18 extending therefrom. the passages 88, 88, 1| and 1.8 in the valve 18, the passages and 84 in the casting 8i, the passage 84 in the wall member 88, and the chamber W. The oil-containing portion of the device also includes the interior portions of the interiltting tubes 88 and 88. the space between the end wall of the cup member 8i, and the disk 88, the openings 88 in the end wall of the cup member, and the space surrounding the tubes 88 and 88 inwhich the springs 88 and 88 are 10- cated. The passage 88 permits oil to pass into and out of the space between the annular member I8 and the adjoining part of the dla'phragm. it being understood that as the diaphragm is vibrated the capacity or this-chamber. changes appreciably. Obviously the diaphragm in eflect atfords a distortable wall for the oil-containing part of the device.

Obviously when the member 8| moves rapidly away'irom solenoid i8 under-the action of the spring, the inertia of the washer 5i and the resistance to its movement caused by the oil body disposed at both sides thereof, causes the washer to lag behind the cup member 8i, so that the check valve provided by these partsis opened. and a certain amount of oil passes through the passages 38 in the moving body 8|. At the end of this outward stroke of the member 8i, the light spring 50 causes the washer 5i again to engage the end wall of the member 3|, so that the oil which has moved through the passages 86 is trapped at the left-hand side of the member 8i, as viewed in Fig. 2; accordingly, during the next inward movement of the diaphragm and the member 3|, some oil from this chamber flows through with extreme rapidity, there is an appreciable circulation of oil through the above-named passages and the valve I into the chamber C.

The plate 00 with its arcuate contact strip 02 also forms part of the electrical control system for the apparatus. This control system can best be understood by reference to the wiring diagrams shown in Figs. 23, 24 and 25. The contact disk 20 may be connected by a lead or conductor 00 to the battery I00 while the contact plate 21 of the make-and-break mechanism is connected to one end of the solenoid I0, the opposite end of which is connected through leads III and I02 to the control switch I03 for the wiper mechanism, which may be located at any convenient point as, for example, adjoining the wiper casing or upon the instrument board of the vehicle. The switch I03 is connected by leads I00 and I to the battery I00 so that when the switch I03 is initially closed, current can flow from the battery through lead 99 to contact plate 20, thence through contact plate 21, the solenoid I0, leads IN and I02to the control switch I00, and from the latter through leads I04 and I05 back to the battery.

Obviously when the circuit is closed in this manner, the coil I0 is energized and the plunger or cup 3i is drawn inwardly, i. e., to the left as viewed in Fig. 2, against the action of spring '09, while the contacts 20 and 21, which are formed of magnetic material and are, therefore, magnetically held together for equal movement against the force-of the spring 29 when the coil I0 is energized, move inwardly together until the contact 21 engages washer 20, the contact 26 thereby being separated from contact 21. The contact 21 is thereupon returned to the limit of its movement to the right, as viewed in Fig. 2, under the influence of the spring 28. Thus the electrical circuit is momentarily broken. Thereupon the spring 49 cooperates with the resilient diaphragm I2 in causing the cup 0i to move in the opposite direction. i. e., toward the right as viewed in Fig. 2, reestablishing contact between plates 20 and 21 and causing reenergizaticn of the solenoid coil I0 whereupon the operating cycle is repeated, it

being understoodthat in practice the armature cup and diaphragm vibrate rapidly.

The contact plates 20 and 21 have surfaces 01 substantial area which engage each other to close the electrical circuit, for example, these areas may be at least of the; order of one-eighth of the area of the diaphragm'within the clamping rings and preferably may be nearer one-quarter of said area. Accordingly, pitting is avoided, and accordingly this make-and-break mechanism may have an exceedingly long operative life.

Obviously the arrangement so tar described permits controllable energization of the solenoid as desired, or opening of the'solenoid circuit so that the electrical power unit is no longer energized. However, if such an arrangement alone were depended upon, the vane, 00, the shaft 1 and the windshield wiper support 0 might'stop at any point in the oscillatory path of these parts. Thus, for example, the windshield wiper blade 0 might until the blade support 0 is brought to one end of its path, whereupon this parallel circuit portion is automatically broken. For this purpose conducting rods 00 and 90 extend through the casting 0| fromthe front of the device, being supported in insulating tubes H0 and III. The inner ends of the rods 90 and 00 support metal arms H2 and Ill, respectively. The arm II2 carries a contact L which constantly engages the strip 02 (Fig. 8) on the insulating disk 05 in all positions or the disk, while the contact arm Ill is of bipartite construction, as shown particularly in Fig. 13, and carries two spaced contacts M and N which are resiliently held in engagement with the contact strip '02 of the disk 05 during 7 the major portion of the path of the disk. The portion of the arm Ill which carries the contact N is provided with a lug III which is engageable with the edge of an extension III of the lug 00 of control plate 00 so'that, for example,

when the plate occupies the position shown in Fig. 8, the contact N is lifted from the strip 02. On the other hand, the contact M is arranged so that it rides of! the end of the contact strip 02 as the disk 00 nears its extreme position, shown stop where it would interfere with the vision of the driver of the vehicle. It is generally recognised that it is desirable to stop the blade at one end of its path, so that, for example, it may be juxtaposed to the upper frame oi the/windshield. To permit this desirable result, the electrical control system is provided with a circuit portion parallel to the switch I03, so that the energization of the electrical power unit can continue for a short period after that switch is opened and the battery I" through the lead .9, the contacts 21 and 20 (assuming that these contacts are in engagement), the coil I0, the leads "I and I20, and the switch I20 (assuming this switch to be closed), the lead I20, the contact L, the contact strip 02, and in parallel through the contacts M and N and thence through the bipartite arm I to the leads I2I and I00 and then to the opposite/side of'the battery.

Obviously. the contacts M andN continue thus toengage the .strip 02 eveniwhen the disk "As at one endof its path. shown for example in Fig. 17. when, however, the control plate 00 moves in the direction indicated by the curved arrow in Fig. 20, the lug 00 on this plate approaches and engages the pin 00 onv the disk. and accordingly the pin 00 is moved to its uppermost position, whereupon the spring 00 is effective in causing theldligktosnapto the positionshowninma an As the plate 02 approaches its position shown in Fig. 8,,itscam-like'extension IIO emaes the lug ill of thebipartite arm m, lifting the corresponding contact N from the strip 02. During the first part of this fraction oi the operating cycle the contact M may continue to engage the strip 02. However, when the disk 00 is snapped over its center position by the spring 00, the strip 02 moves out of engagement with the contact M as the disk rapidly approaches this end of its path. Obviously this occurs as the vane 00 and the wiper support I are practically at one end of their oscillatory path. Under these conditions, it is evident that the circuit through the leads I23 and I2I is broken so that operation of the power unit is thus interrupted, if the switch I02 has been opened. Accordingly no matter what the position of the vane 00 and the support I I opened just as the plate has reached this position,

the operation of the power unit will immediately be terminated. Should the control switch I03 be opened just as the control plate 83 starts away from the position shown in Fig. 8, i. e., is moving in the direction of the curved arrow shown in Fig. 16, the operation of the power unit will be immediately interrupted unless the plate "has moved far enough to permit the contact N to return into engagement with the strip 92. If

- this has occurred the parallel. circuit portion is closed and the mechanism will complete substantially an entire cycle until the plate 83- and disk 85 again reach the positions shown in Fig. 8.

It is thus evident that when the switch I03 is opened when the parts 85 and 83 are near the positions shown in Fig. 8, the further operation of the power unit is prevented if the switch is opened after the disk 85 has been snapped to the position shown in Fig. 8 and before the plate 88 has moved suiliciently to permit the contact N to resume engagement with the strip 92. Thus under any operating condition the vane 88 and the wiper support are stopped in a position which is substantially at the extreme end of the oscillatory path, the maximum possible spacing from this extreme position being determined by the angular movement of the plate 83, which sufiices to cause the movement of contact N into and out of engagement with the strip 82.

While the leads I23 and I25 mignt be connected directly together in order tov permit operation of the electrical control system in this manner I prefer to connect these leads through the ignition switch I24 so that the wiper and the wipe'i'blade support 5 can be manually moved to any desired position when the motor ignition is'cut of! and, for example, the windshield is being cleaned. Under such conditions the blade will remain in the position to which it was moveduntil the ignition switch I24 is closed, whereupon the circuit will be closed through leads I23 and I2I, causing the electrical power unit to operate until the blade has reached the desired inoperative position, unless, of course, the blade has been left in this position. I I

It will of course be understood that the electrical connections shown in Figs. 23, 24 and 25 are diagrammatic in character and that in practice, for example, the contact arms H2 and II are connected to the remainder of the electrical circuit through the rods 98 and 99 and that other portions of the circuit may be provided by suitable metallic parts of the device or of the vehicle to which is is secured or by wiring not specifically illustrated herein.

Furthermore, it will be evident that the circuit for the magnetic field comprises the cup-like member 3|, the plate 30, the diaphragm I2, the annular members I4 and II, a portion of the wall of casing I and the member 40 with its collarlike extension 40 The part 40" in effect affords a partial core member for the magnetic coil I0, so that the electrical unit partakes partially of the nature of a conventional solenoid assembly and partially of the nature of a conventional electromagnet assembly, the plunger 8i having the function both of the plunger of a solenoid and of the armature of an electromagnet.

In the normal operation of a windshield driving mechanism of this character, it is evident that when the coil III is energized the armature cup 8| is moved back and forth rapidly and a corresponding rate of vibration is imparted. to the diaphragm I2 which forms a distortable wall for the oilcontaining portion or the apparatus. When the cup moves away from its innermost position under the action of the heavy spring 49, the inertia of the washer 5| andthe pressure of the oil imposed 1 through the openings 36 tend to cause the washer to lag behind the armature cup 3i so that the check valve provided by the washer ii is opened and a certain amount of oil passes to the side of the cup adjoining this washer. vWhen the cup Si is near the outer end of its path, it is reengaged by the washer 50 so that the valve is closed after a certain additional amount of oil has been trapped .upon that sideof the cup. Thus as the cup moves inwardly, there is a tendency for the oil to be pumped through the passages 54, 82 and 64 and through either the supply passage 68 or the supply passage 68 of the valve Wand thence through either the passage H or I3 of the casting 6 I and into the corresponding side of the chamber C. Since the vibration of the cup 3| occurs at high speed, a constant current of oil is circulated in this manner into the chamber C, imposing pressure upon one side of the blade 80 and causing movement of the same, the shaft 1, and the wiper support 5. As the blade is moved in this manner, it presses oil out of the opposite side of the chamber C to replace oil which passed from the cham- .ber W and from the interior .of theinterfitting movement or the vane 80 in the opposite direction.

Thus the direction of movement of the vane is automatically reversed as it approaches each end of it path. It is evidenizas has been described,

when the control switch I I13 is opened, the operation of the mechanism will continue unless or until the blade support 5 and the blade 6 have reached one end of their oscillatory path, when the contacts M and N are both out of contact with the contact strip 92, whereuponthe operation of the electrical power unit is interrupted.

It is evident that the present invention affords a mechanism particularly suitable for actuating a windshield wiper, although I am aware that such mechanism may also be advantageously employed for various other purposes. In'the preferred windshield wiper arrangement the electromagnetic unit may operate independently or the speed of the motor of the vehicle or of the degree of vacuum in the inlet manifold thereof. However, the electromagnetic unit avoids the troublesome commutators and brushes which have heretoi'ore been employed in electrically driven wipers, while the contact plates afforded by the present invention permit the provision of a make-andbreak mechanism which has a very long operative life. without necessity for attention or replacement of parts.

Furthermore, the arrangement of the hydraulic power transmitting system permits the electromagnetic unit to be-eflective in imparting an oscillatory movement to the wiper support or the parts is avoided and the necessity or desirability of lubrication of such. parts is eliminated.

The present invention also affords a simple and convenient control arrangement wherein the control for the valve which directs the operating fluid to opp site sides of the vane is associated with a portion of the electrical circuit, so that when the control switch for the wiper is opened the movement of the wiper support is automatically continued until the wiper stops at one end of its path.

I claim: I

1. Mechanism of the class described comprising a casing, an electro-magnetic power unit in said casing, a vibratory pumping member, a check valvecarried by said member, a liquid-containing system within the casing enclosing said pumping member and valve, said member and valve being actuable in response to energization of the unit ing said unit, said circuit including a control switch and including a circuit portion parallel to said switch for causingthe continued operation of the unit until the vane reaches one end of its path should the control switch be opened when the vane is not at the said one end, said parallel circuit portion including a pair of contacts. one of which is carried by said part and disengages the other contact when said part is moved with a snap action beyond a certain point in one direction.

2. Mechanism of the class described comprising a casing, an electro-magnetic power unit in said casing, a vibratory pumping member, a check valve carried by said member, a liquid-containing system within the casing enclosing said pumping a member and valve, said member and valve being actuable in response to energizatlon of the unit to cause circulation of liquid through the system, said system including a vane chamber, a vane in said chamber, means including a valve to direct the liquid first against one surface of the vane and then against an opposite surface thereof to cause the vane to move back and forth in said chamber, an oscillating shaft extending from the chamber and secured to said vane, an electric circuit for energizing said unit, said circuit including a control switch and a circuit portion parallel to said switch for causing the continued operation of the unit until the vanereachesone end of its path should the control switch be opened when the vane is not at the said one end, said parallel circuit portion including a pair of normally engaged contacts, a part movable member and valve, said member and'valve being actuable in response to energization of the unit to cause circulation of liquid through the system, said'system including a vane chamber, a vane in said chamber, means including a valve to direct theliquid first against one surface of the vane and then against an opposite surface thereof to cause the vane to move back and forth in said chamber, an oscillating shaft extending from the chamber and secured to said vane, an electric circuit for energizing said unit, said circuit including a control switch and including a circuit portion parallel to said switch for causing the continued operation of the unit until the vane reaches one end of its path should the control switch be opened whenthe vane is not at the said one end, means movable with said shaft, a part engageable by said means as the latter approaches each end of its path, a spring to cause the snap action of the part when thus engaged by said means so that the part thereupon remains in the position to which it was-snapped until again engaged by said means, said parallel circuit portion including a pair of normally engaged contacts one of which is carriedby said part whereby, when it thus snaps to said position, the contacts are operated 4. Mechanism'of the class described comprising a casing, an electromagnetic power unit in said casing, a vibratory pumping member, a check valve carried by said member, a liquid-containing system within the casing enclosing said pumping member and valve, said member and valve being actuable in response to energization of the unit to cause circulation of liquid through the system, said system including a vane chamber, a vane in said chamber, means including a valve to direct the liquid'first'againstone surface of the vane and then against an opposite surface thereof to cause the vane to move back and forth in said chamber, an oscillating shaft extending from the chamber and secured to said vane, an electriccircuit for energizing said unit, said circuit including a control switch and including a circuit I portion parallel to said switch for causing the continued operation of the unit until the vane reaches one end of its path should the control switch be opened when the vane is not at the said one end, means movable with said shaft, a part engageable by said means as the latter approaches each end of its path, a spring to cause the snap action of the part when thus engaged by said means so that the part thereupon remains in the position to which it was snapped until again engaged by said means, said parallel circuit portion including a pair of normally engaged contacts'one of which is carried by said port whereby, when it thus snaps to one end of its path, the contacts are separated said parallel circuit portion including a second pair of normally engaged contacts parallel to the last-named pair of contacts, said second pair being separated and restored to normal engagement by said means as it approaches and leaves respectively one end of its path, whereby the parallel circuit portion is closed by the second pair while said part remains-in said position, as the said vane is moved away fro'mthe end of its path.

5. Mechanism of the class described comprising a casing, an electromagnetic power unit in said casing, a pumping member adapted to be reciprocated by said power unit, a fluid circulating system in which system said pumping member is located, check valve means cooperating with said pumping member to control the direction'of fiow of fluid in said system under the influence of said pump. ing member as actuated by said power unit, said system including .a vane chamber, a vane in said chamber, valvular means for directing fluid under in said system nrst against one surface of said vane and then against the opposite siniace thereo! whiIe exhausting fluid from the resp tively opposite laces thereof whereby to cause oscillation of said vane, a shaft extending from said chamber and secured to said vane for oscillation therewith, an electric circuit for energizing said power unit, said circuit including a control switch and including a circuit portion parallel to said switch for causing continued operation of the unit until the vane reaches one end of its path of movement should the control switch be opened.

whenthevaneismidwayoisuchpath'meens movable with said shait. a part ensaseable with said movable-means as the latter approaches each endotitspath,aspr instocauseasnapaction or said part when thus eng sed bysaid movable means so that said part thereupon remains in thepositiontowhichitwassnanpeduntilagain enlased by said movable means, a connection between said part and valvular means for eriecting simultaneous operation thercoi, and a pair oi nor-.

- with said snap action mechanism when the latter is in one oi its extreme positions of movement whereby to move it to open circuit position. 

